The present invention relates to a hearing aid of the type in which the sound is amplified and, via air conduction, is made to stimulate the eardrum to vibrate.
For persons with impaired hearing, the hearing aids mainly used today are those based on the principle that the sound is amplified and conveyed into the auditory meatus and stimulates the eardrum from the outside. In order to prevent feedback problems in these appliances, the auditory meatus is almost completely plugged by a hearing plug or by the appliance itself. This causes the user a sensation of pressure, discomfort and sometimes even eczema.
It is already known to use hearing aids which leave the auditory meatus free, see for example U.S. Pat. Nos. 5,411,467 and 5,318,502, which hearing aids are both connected to the inner ear. Such a connection, however, necessitates an intervention on the inner ear, which entails a relatively complicated surgical implantation.
It is also already known, from U.S. Pat. Nos. 5,282,858 and 4,988,333, to secure part of the hearing aid on the bones of the middle ear. Although such a solution leaves the auditory meatus free, it nevertheless requires an extensive surgical implantation with intervention on the bones of the middle ear.
The object of this invention is to make available a hearing aid of the type in which, via air conduction, the sound stimulates the eardrum to vibrate, at the same time as the auditory meatus is left free, and without intervention on the eardrum, the inner ear or the bones of the middle ear.
According to the invention, the sound is conveyed in to the middle ear via a hose, tube or the like which has been permanently implanted surgically in the skull bone in order in this way to stimulate the eardrum to vibrate from the inside. By means of the invention, it is possible for an air-conduction appliance to be used at the same time as the auditory meatus is left free. The sound vibrations in the air in the middle ear set the eardrum in vibration. The eardrum is stimulated in this way from the inside instead of from the outside, i.e. a direct acoustic coupling to the middle ear. The advantage of this is that the auditory meatus can then be left free since no hearing plug is needed, as is the case in traditional hearing aids. In this way, discomfort and irritation of the auditory meatus can be avoided.